This is a continuation-in-part of U.S. patent application Ser. No. 09/563,268 entitled “Needle Sheath”, filed May 3, 2000 now U.S. Pat. No. 6,524,278, which is a continuation of PCT/GB99/02175, filed Jul. 7, 1999.
BACKGROUND OF THE INVENTIONThis invention concerns a sheath for the needle of a hypodermic syringe.
Hypodermic syringe assemblies are usually provided with a protective sheath covering the needle for its protection until the syringe is required for use.
It is a common, though by no means universal, practice to change the needle of a syringe after filling and before administration of the injection because of a perception that the original needle may become blunted, bent or subjected to loss of needle lubricant during the filling operation, for example by insertion through the rubber cap of the vial, contaminated with a foreign substance, for example latex from such a cap or rendered unsterile, or to suit filling requirements for rapid filling of the syringe by using a large bore filling needle.
In the case of syringes with provision for retraction of the needle after use as disclosed for instance in our prior U.S. Pat. No. 5,782,804, the needle assembly tends to be specially designed for this purpose and it is not therefore practical to contemplate changing needles after filling the syringe and before administering the injection.
There are also concerns over the risks of drawing in fragments or slivers of material, e.g. glass, when the syringe is filled from for example an ampoule following breaking of a glass or other cap of the ampoule. Moreover, if the same needle is used to fill the syringe and also administer the medication, some injection fluid may be present on the outside of the needle which may be undesirable since some substances for injection can be irritating to the skin.
Further, it is often desirable to have the ability to administer an injection by either a retractable needle or by means of an intravenous means.
SUMMARY OF THE INVENTIONThese matters are addressed by various aspects of the present invention. The invention has particular, but not necessarily exclusive, application to the type of syringe which incorporates a needle retraction mechanism and is thereby not readily amenable to the possibility of needle change between syringe filling and admistration of the injection. Further, an arrangement is disclosed including a filling spike and an adapter for intravenous injection.
According to one aspect of the present invention there is provided a hypodermic syringe having a barrel, a hollow fluid dispensing needle which projects from the barrel, means for retracting the needle after use from the projecting position to a retracted, inaccessible position, and a sheath which is removably engageable with the syringe to sheath the needle and provide an interior zone for communication with the internal bore of the needle, the sheath being apertured to admit liquid to said zone whereby liquid drawn through the needle into the syringe first passes into said zone.
The sheath may be shaped or adapted so as to be capable of penetrating the rubber cap of a vial or the like. To this end, it may be provided with a pointed end or a separate needle. In this way, the sheath may be used as a needle during filling of the syringe thereby avoiding any risk of compromising the needle proper as discussed above through having to use the needle proper to pierce a rubber cap for instance.
When used with a syringe having needle retraction means, the needle need only be exposed during the time that it is actually in use for the administration of an injection. At all other times, including filling of the syringe, the needle may be effectively inaccessible thereby considerably reducing the risk of needle stick injuries since the sheath need not be particularly sharp as it is only used for filling the syringe.
The sheath together with its pointed end or filling needle may be used together with an adapter whereby, after filling of the syringe by means of the pointed end of the sheath, the adapter can be directly connected to an intravenous injection system. Alternatively, a retractable needle may then be used to inject the medicine into a patient.
According to a second aspect of the present invention there is provided a sheath which sealably connects over the needle of a hypodermic syringe and is optionally shaped or adapated to penetrate the rubber cap of a vial or the like, the sheath being apertured to allow the ingress of liquid to an interior zone thereof whereby liquid drawn through the needle into the syringe first passes into said zone, filter means being incorporated in the sheath to exclude the entry of particulate material into said zone.
According to a further aspect of the present invention there is provided a sheath which sealably connects over the needle of a hypodermic syringe and is optionally shaped or adapated to penetrate the rubber cap of a vial or the like, the sheath being apertured to allow the ingress of liquid to an interior zone thereof whereby liquid drawn through the needle into the syringe first passes into said zone, needle-wiping means being incorporated in the sheath and arranged so that removal of the sheath automatically wipes the needle to remove any excess liquid on the outside thereof.
According to a still further aspect of the present invention, there is provided a sheath and an adapter. The adapter can be directly connected to the barrel of the syringe, and the sheath can be attached thereto. The pointed portion of the sheath can be used to fill the syringe. Thereafter the sheath can be removed and the adapter can be directly connected to a needleless I.V. access system. Alternatively, the adapter may be removed and a retractable needle assembly can be connected to the barrel to administer the medicine to a patient.
The sheath may, if desired, incorporate both filter means and needle-wiping means.
The filter means may be be take take various forms—for example the filter means may be composed of fibrous material or it may comprise a sintered plastics material. Examples of suitable materials include hydrophilic and hydrophobic materials. The plastics materials employed may for instance be selected from the following, including combinations thereof: nylon, polyurethane, polyester, polyolefin, polyethylene, PTFE, acetal, acrylonitrile butadiene styrene and styrene acrylonitrile. Most of these materials can be processed in a number of ways with the exception of PTFE which will generally be sintered. The other materials can be moulded with a foaming agent to give an open cell foam with controllable porosity or made into a non-woven fibrous mat by using a binder compound. Suitable filter materials for use in the present invention are obtainable from for example GVS Srl of Bologna, Italy and Filtertek BV of Limerick, Eire.
The needle-wiping means is conveniently in the form of a thin web or membrane through which the needle extends in use so that when the sheath is removed from the sheath, the marginal edge of the web or membrane surrounding the needle is drawn along the outside the needle thereby wiping the same. Preferably the web or membrane is composed of a resilient material and tends to contract around the needle by virtue of its resilient nature. Suitable materials for the membrane or web include elastomers such as silicones or silicone-based materials.
The sheath may have a pointed end to facilitate penetration into a vessel, e.g. via a rubber seal or cap provided on the vessel.
The sheath may have at least one aperture through its wall above the pointed end and/or it may have an aperture at its pointed end.
The sheath may be protected before use by a removable guard which is conveniently in the form of a part cylindrical wall.
The guard may be integral with the sheath and removable at one or more frangible connections.
The sheath may be removably attachable to the syringe through a push-on/pull-off friction fit or snap fit or through a threaded connection or a bayonet-type connection.
The sheath may be formed from a metal or a plastics material.
BRIEF DESCRIPTION OF THE DRAWINGSThe invention will be further apparent from the following description with reference to the several figures of the accompanying drawings which show, by way of example only, several forms of sheath embodying same. In the drawings:
FIG. 1 shows a cross-section through the sheath;
FIG. 2 shows a cross-section through the sheath ofFIG. 1 in position over the needle of a hypodermic syringe;
FIG. 3 shows a perspective view of the sheath ofFIGS. 1 and 2;
FIG. 4 is a fragmentary sectional view showing one specific form that the wiping membrane may take;
FIG. 5 is a fragmentary sectional view showing a needle-wiping membrane in the form of a disc which provides sealing engagement between the sheath and the nose of the syringe barrel;
FIG. 5A is a sectional view showing the disc ofFIG. 5;
FIG. 6 is a fragmentary sectional view illustrating another form of needle-wiping membrane and a one-way valve arrangement;
FIG. 6A is a similar view to that ofFIG. 6 showing the membrane pierced by the needle of the syringe;
FIG. 7 is diagrammatic, exploded view of another embodiment of the sheath in which the sheath is of two-part construction including a separate filling needle;
FIG. 8 is fragmentary sectional view of the syringe showing the same in at a stage in which the plunger has completed part of its forward travel;
FIG. 9 is a view which is rotated 90 degrees relative to that of FIG.8 and showing the syringe in the same condition as inFIG. 8;
FIGS. 10 to15 are views similar to that ofFIG. 8 but showing successive stages of plunger forward travel up to and including completion of drug dispensing and operation of the needle retraction mechanism;
FIG. 16 is a perspective view of a syringe barrel and plunger and an adapter;
FIG. 17 is a cross-sectional view of a syringe, an adapter, and a sheath;
FIG. 18 is a view similar toFIG. 16 with the adapter attached to the syringe;
FIG. 19 is a perspective exploded view of a syringe, an adapter, and a sheath;
FIG. 20 is an enlarged perspective view of the adapter and sheath ofFIG. 19;
FIG. 21 is a sectional view of an adapter and a sheath which are connected to each other;
FIG. 22 is a perspective view of a syringe with an adapter secured thereto and an intravenous connector before it is connected to the adapter;
FIG. 23 is a view similar to that ofFIG. 22 with the intravenous connector connected to the adapter;
FIG. 24 is a view similar toFIG. 23 with the plunger fully depressed.
FIG. 25 is a perspective, exploded view, of a syringe and retractable needle assembly; and
FIG. 26 is a view of an assembled syringe and retractable needle assembly, before the plunger is depressed.
Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates preferred embodiments of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner.
DESCRIPTION OF THE PREFERRED EMBODIMENTSReferring now toFIGS. 1 to3 of the drawings, thesheath10 is formed, e.g. from metal or a plastics material, with asocket11 at its rear end for engagement with the end cap E of a hypodermic syringe having a needle N, barrel B and plunger P. The sheath may engage with the syringe with push-on/pull-off friction fit. Anannular seal12 is provided on the end of thesheath10 which abuts the forward face of an annular flange F at the rearward end of the cap E.
Thesheath10 has ahollow interior14 which accommodates the needle N of the syringe. Thesheath10 terminates in a pointedforward end15 capable of penetrating the rubber cap of a vial or being inserted into an ampoule whose cap has been broken therefrom. The sheath is apertured at a location in close proximity to thepointed end15, the aperture being formed by an axially extending elongate slot. In the illustrated embodiment, two such slottedapertures16 are provided on diametrically opposite sides of the sheath.
Aguard17 in the form of a part cylindrical wall is formed integrally with thesheath10 and is removable from the sheath at afrangible connection18. The guard protects the sheath and prevents its pointed end from damaging and thereby compromising the sterility of primary packaging in which the syringe is supplied. Theslot19 in the wall enables the guard to be broken away without damaging the sheath which can pass through theslot19 during this operation.
A filtering material depicted byreference numeral20 is provided within the sheath at a location between the forward end of the needle and theapertures16 so that only liquid that has passed through the filtering material is accessible by the needle during filling. In this way, particulate materials, such as glass slivers, splinters or shards that may have inadvertantly contaminated the injection fluid are excluded by the filtering material thereby eliminating any risk of fine slivers of glass entering the syringe during filling thereof. The filter material may take various forms, e.g. it may be in the form of a fibrous extrusion or a porous plastic plug.
At a suitable location, the sheath is provided with needle-wiping means which, in the illustrated embodiment, is in the form of a thin web of material ormembrane22, e.g. an elastomer such as a suitable silicone, extending across the interior of the sheath so that, when the latter is assembled to the syringe, the needle passes through the web. The web may be provided with a pre-formed hole through which the needle passes or the hole may be formed by the needle automatically during the act of pushing the sheath on to the syringe. In either case, the arrangement is such that the marginal edge around the hole in the web contacts the needle around its circumference so that, when the sheath is subsequently removed, the marginal edge cleans off any excess liquid adhering to the outside of the needle following the filling operation. Themembrane22 may be of an elastomeric material such as silicone rubber.
In use, the syringe is removed from its primary packaging and the barrel B of the syringe filled in known manner by retraction of the plunger P after insertion of the forward end of the sheath through the rubber cap of a vial or insertion of the forward end into an ampoule whose cap has been broken therefrom. During filling, the injection liquid passes through the filtering material before entry into the needle. Thesheath10 is then removed and discarded to enable administration of the injection in known manner. During sheath removal, the outside of the needle is automatically wiped clean.
It sometimes happens that medical staff use a filling needle of larger bore than the injection needle for the purposes of filling the syringe—particularly when the bore of the injection needle is particularly fine. The possibility of removing thesheath10 and original needle before replacing thesheath10 and using it as a filling needle should not be overlooked.
Referring now toFIG. 4, the needle-wiping means40 may in one embodiment of the invention be in the form of a disc comprising aperipheral ring42, e.g. of O-section, and an integralcentral web44. The disc is assembled to the sheath by seating the O-ring firmly, preferably with a sealing engagement, in anannular groove46 formed in the wall48 of thesheath10. Typically the disc comprises an elastomeric material. When the sheath is assembled to the syringe, the needle will penetrate the central web which, by virtue of its elastomeric nature, will seal around the outer periphery of the needle. The web may be initially imperforate or it may be preformed with an aperture through which the needle passes. In this way, when the tip of the sheath is inserted into a liquid to be drawn into the syringe, the interior volume within the sheath between thecentral web44 and the tip of the sheath may be made airtight to allow suction to be developed.
FIGS. 5 and 5A illustrate another form of needle-wipingdisc50 designed to effect a seal with thenose58 of the barrel B. Thedisc50 comprises aweb52 from one face of which an upstanding generally O-section ring54 projects. Thering54 seats in agroove56 of thesheath10 so that, on assembly of the sheath to the barrel, thering54 is engaged between the sheath and barrel to form an air-tight seal. As in the previous embodiments, the disc is fabricated from an elastomeric material and the web is sufficiently thin that it is readily pierced by, and seals around, the needle during assembly of the sheath to the barrel. In this instance, sealing is effected by thedisc50 at two locations, namely around the needle itself and also at the point of contact with thenose58 of the barrel B.
In the embodiment ofFIGS. 6 and 6A, in addition to the seal between the sheath and the interior of the needle, there is also a one-way valve which ensures that the flow of fluid can only take place in one direction when the sheath is fitted to the syringe. InFIG. 6, those parts in common withFIGS. 1 to3 are depicted by the same reference numerals and will not be described further. As shown inFIG. 6, a one-piece moulding60 is located within the interior of the sheath and forms a one-wayvalved septum chamber62 comprising aweb64 which extends across the cross-section of the sheath to form a seal which isolates the lower interior volume of the sheath extending between theweb64 and thetip15 of the sheath from the upper interior volume extending between theweb64 and the nose of the barrel B. The moulding includes a generallycylindrical side wall66 which nests within the interior of the sheath and awall68 which includes anenlargement70 forming a valve member normally seats against and makes sealing engagement with the upper end of thepassageway72 extending through the projecting spike-like formation of thesheath10. Thewall68 only extends only partway across the diameter of the moulding in such a way that it can flex towards thewall64 by flow of liquid through the spike-like formation ofsheath10. In the absence of liquid ingress, thewall68 biases thevalve member70 to its closed position in which it closes the upper end of the hollow spike-like formation.
In use, when the sheath has been assembled to the syringe, the needle N pierces theweb64 and penetrates into the septum chamber62 (see FIG.6A). When thecylindrical guard17 has been removed and the tip of sheath is immersed in a liquid, the syringe is operated to aspirate the liquid through the needle N so that the resulting suction effect draws thevalve member70 away from itsseating72 at the upper end of the spike-like formation to draw the liquid upwardly into theseptum chamber62 and then into the needle to fill the syringe. Also, liquid drawn into the needle N in this way must first traverse thefilter20 and any glass shards or contaminants present may be excluded from passing into theseptum chamber62 and hence the syringe. Flow of liquid in the opposite direction is prevented since such flow will tend to cause thevalve member70 to make sealing contact with theseat72 at the upper end of the spike-like formation and thereby block liquid flow.
Subsequently thesheath10 may be removed from the syringe prior to using the syringe to administer an injection to the patient. In the course of removing the sheath theweb64, which by virtue of its resilient nature contracts around the needle, is drawn along the forward extremity of the needle thereby wiping any excess liquid from the exterior of the needle before it is used to inject a patient. It will be observed that the one-way valve ensures that the injection can only be administered after the sheath has been removed from the syringe thereby eliminating the possibility of an injection being administered while the sheath is still in place.
In the embodiments thus far described, the sheath is generally spike-shaped so that it can be used to penetrate or pierce the rubber cap of a vial directly.FIG. 7 illustrates an embodiment in which the sheath is of two-part construction comprising anadaptor section80 which may incorporate the wiper and/or the filter and a separate auxiliary needle-carryingsection82. Theadaptor section80 at itsupper end84 is adapted to be releasably engaged with thenose86 of the syringe barrel B. For example, it may be a simple push fit (in the direction X) on to thebarrel nose86 and, when so fitted, it may form a fluid-tight seal although this is not essential if the wiping membrane serves this purpose. As in the embodiment ofFIGS. 6 and 6A, thewiper membrane64 is embodied in a one-piece moulding60 of an elastomeric material which also incorporates a one-way valve70 co-operating withseat72, the arrangement being such that when the sheath is fitted to the barrel, the needle N pierces themembrane64 and communicates with the septum volume62 (in the manner shown in FIG.6A). Themembrane64 serves the dual function of providing a seal around the needle N when the sheath is correctly assembled to the syringe and wiping the needle N on removal of the sheath from the syringe.
Theforward end87 of theadaptor section80 and the needle-carryingsection82 are designed to fit together with a sealing engagement, e.g. by means of a luer slip or luer lock fitting. Theforward end87 accommodates aplug20 of filter material so that liquid entering theseptum chamber62 must first traverse the filter thereby excluding foreign matter such as glass shards that might be present when the syringe is filled from a glass ampoule. The needle88 ofsection82 is employed purely as a filling needle which is used to pierce the rubber cap of a vial for example, liquid being drawn into the syringe via the needle88, one-way valve70,septum chamber62 and needle N by appropriate operation of the syringe plunger. After the filling operation has been completed, thesection82 is removed and discarded while theadaptor section80 can be left in place until the syringe is used to administer the injection.
In each of the embodiments described above, the syringe may be of the type provided with a needle retraction mechanism whereby, after administration of the injection, the needle N is retracted from the projecting position illustrated to an inaccessible position so as to prevent needle stick injuries. A suitable needle retraction mechanism for use in the present invention is that disclosed in U.S. Pat. No. 5,782,804, the entire disclosure of which is incorporated herein by this reference.
One embodiment of the needle retraction mechanism will now be described with reference toFIGS. 8 to15. The barrel B of the syringe includes a mountingportion98 for the needle N, having a through passage at the inner end of which is an upstandingannular wall99. The inner end of the needle N is axially captive with ahub118 having anannular flange119 which locates an O-ring120. Thehub118 provides a passageway for the needle N.A compression spring128 surrounds the needle so as to bias thehub118 and hence the needle rearwardly. When assembled, thespring128 is in an almost fully compressed condition and is maintained in that condition by the O-ring120 which is compressed between annular wall portion132 and thehub118. The O-ring120 is prevented from movement in the rearward direction by acrown136 which is, itself, blocked from rearward movement by projections137 (see FIG.9). Thecrown136 comprises aring138 provided with a pair of rearwardly directedextensions140 of arcuate configuration, the dimension of thering138 and the spacing of the extensions being sufficient to allow the needle hub to pass during the needle retraction phase as described below. Theextensions140 project into the interior of the barrel when the syringe is in its pre-use condition shown in FIG.8. As seen inFIG. 8, there is an annular space135 forwardly of the O-ring120.
The plunger P of the syringe is hollow having its rear end (not shown inFIGS. 8 to15) closed by a cap. The forward end of the plunger P is provided with aninsert142 which engages firmly in the plunger and is encircled by seal143 which contacts the internal surface of the barrel B. Theinsert142 constitutes a “bursting disc” device and includes anannular rim portion150 and a central generally frusto-conical formation orcone152 which is connected to therim portion150 in a frangible fashion, e.g. by a thin web of material which can be ruptured or broken away when thecentral cone152 is stressed axially relative to the rim portion. In operation, the syringe is charged with liquid via thesheath10 as described previously to achieve its ready-for-use condition in which the plunger P is drawn back rearwardly relative to the barrel B. After removal of the sheath10 (not shown inFIGS. 8 to15), the plunger P is caused to move forwardly relative to the barrel (i.e. to the left as seen inFIGS. 8 to15) and the advancing plunger is effective to expel liquid through the needle N.
FIG. 10 shows the positions of the parts after the plunger P has been advanced sufficiently to bring the leading end face of therim portion150 into abutment with the trailing ends of theextensions140. Further forward travel of the plunger P is effective to push thecrown136 forwardly (by virtue of contact between therim portion150 and the extensions140), which forward movement is transmitted to theneedle hub118 through the O-ring120 thereby taking up the small amount of axial play initially present between theflange119 and the trailing end of theannular wall99 and terminating any further forward movement of the needle hub. Withhub119 blocked bywall99, continued forward movement of the plunger P is then effective to begin displacing the O-ring120 as shown inFIG. 12, i.e. the O-ring then begins to expand over theflange119 of the hub.
As shown inFIG. 13, the foward end of thecone152 eventually comes into contact with the rear face of theneedle hub118. At this stage, the O-ring120 is still effective to maintain a seal and drug continues to be expelled from the barrel via a slot154 in the forward end face of thecone152. Once thecone152 has come into contact with theneedle hub118, continued pressure applied to the plunger in the forward direction is effective to stress the thin web interconnecting thecone152 and therim portion150 and deform the web towards its breaking point. Before the web breaks however, the arrangement is such that web integrity is maintained until such time as O-ring120 has been fully pushed over theflange119 and onto the annular wall99 (seeFIG. 14) so as to disable the coupling action afforded by the O-ring between the needle hub and the crown. The procedure is completed by breakage of the thin web thus allowing thespring128 to expand and drive the needle hub and connected needle N rearwardly together with the broken awayformation152 into the interior of the plunger thereby rendering the needle inaccessibly concealed wholly within the syringe as shown in FIG.15.
It will be seen that the needle N need only be exposed during the administration of the intended injection. At all other times, the needle may be either sheathed with the aid of sheath or inaccessible as a result of being retracted into the plunger (and hence the barrel).
Referring now toFIGS. 16-23, there is shown an alternative embodiment of the invention. This embodiment comprises a needle-free injection system. In this embodiment, as best seen inFIGS. 16 and 17, anadapter166 is provided for use with a barrel B and with a fillingspike208 to draw medication into the barrel and to thereafter inject it into a patient by way of anintravenous fitting226 as best seen inFIGS. 22 and 23.
More particularly, barrel B is provided with aprojection160 andexternal threads162, such as for instance, for use with a luer slip or luer lock fitting. Further,adapter166 is provided withinternal threads164 for engagingexternal threads162 ofbarrel B. Adapter166 includesexternal fluting167 wherebyadapter166 can be more easily gripped for securement tobarrel B. Adapter166 also includes aninternal extension171 which defines ahollow space173 together with the outside wall ofadapter166.Windows170 are provided by the use of side-cores inmolding adapter176 to enable the formation of internal threads on the adapter.
Projection168 and the outside wall ofadapter166 also form ahollow space175. The inside surface of the outside wall ofadapter166 is provided withinternal threads172. As can be seen inFIG. 18,adapter166 can be threadedly engaged with barrel B by engagement ofinternal threads164 withexternal threads162 of barrel B. Such threads may provide a luer lock or other suitable threaded engagement.Threads172 permit a fillingspike208 to be threadedly attached toadapter166 for filling barrel B. Alternatively, anintravenous adapter226 can be threadedly connected tointernal threads172 ofadapter166 when it is desired to inject medicine from barrel B into a patient. It can also be seen thatprojection168 has anaperture178 and is hollow and defines a hollowinterior passageway176 which extends completely throughadapter166. Thus, fluid can be drawn into barrel B throughpassageway176 when fillingspike208 is connected toadapter166, as shown inFIG. 21 or alternatively can be expelled throughpassageway176 through anintravenous fitting226, as further explained hereinafter.
Referring further to FIGS.17 and19-21, fillingspike208 includes ahollow sheath210.Sheath210 includes apointed end215 and one ormore filling slots216 inpointed end215. Fillingspike208 further includes acentral portion219 whereby fillingspike208 can be gripped and manipulated.Windows212 are provided as side-cores in the molding process to maintain a constant material thickness. Additionally, aguard217 is provided which is connected tocentral portion219 by means of afrangible connection218.Guard217 can be removed from fillingspike208 by fracturingfrangible connection218. Anextension213 is also connected tocentral portion219 and includesexternal threads214, whereby fillingspike208 can be threadedly connected toadapter166.Threads214 and172 could define a luer type fitting. As can be seen inFIG. 21, fillingspike208 may be connected by threaded engagement toadapter166, which in turn can be secured to barrel B as shown in FIG.18. Thus, in this configuration the syringe is ready to be filled with medicine.Guard217 would be removed by fracturingfrangible connection218 wherebysheath210 is exposed and can be inserted into a container in the manner heretofore described.
The filling operation of barrel B would include applying pressure to thumb pad T whereby plunger P is moved into barrel B, beforesheath10 is inserted into a vial (not shown) which includes the medicine. The syringe can be manipulated by having a user place two fingers below grip G of barrel B whereby pressure can be applied to thumb padT. Filling spike208 is now inserted into the vial or other container which contains the medicine. The plunger is then moved backward by having a person apply a pulling force on thumb pad T and plunger P. Once barrel B has been filled with medicine, fillingspike208 can be removed by disengagingthreads214 fromthreads172. Thereafter, anintravenous fitting226 and associatedtubing228 can be connected toadapter166 by threaded engagement ofthreads229 withinternal threads172 as shown inFIGS. 22 and 23. The other end oftubing228 is connected to a patient by conventional means such as an I.V. catheter or other I.V. access system. The medicine in barrel B can then be injected throughtubing228 and into the patient by applying pressure to thumb pad T and forcing piston P into barrel B, thereby expelling the medicine from the barrel, throughadapter166,intravenous fitting226,tubing228, and into the patient.
Referring now toFIGS. 25 and 26, it should be noted that, rather than injecting medicine through a needleless injection system as shown inFIG. 24,adapter166 may be removed from barrel B, once medicine has been drawn into the barrel. Aretractable needle assembly230 can then be secured torejection160 of barrel B, as shown inFIG. 26, so that plunger P can be depressed as described hereintobefore and the medicine can be injected into a patient through needle N. It should also be noted thatthreads232 would have advantageously be such thatneedle assembly230 cannot be removed from barrel B, once it has been attached. In that arrangement, once the medicine has been ejected from barrel B, the automatic retraction mechanism described hereintofore will cause needle N to be retracted into the plunger whileretractable needle assembly230 cannot be thereafter removed from the barrel for safe disposal of needle N.
While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.